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文末提到了回收机制、移除时间通知等内容，许多朋友也挺感兴趣，这次就这两个内容再来分析分析。

在开始之前先补习下 Java 自带的两个特性，Guava 中都有具体的应用。

Java 中的引用首先是 Java 中的引用。
在之前分享过 JVM 是根据可达性分析算法找出需要回收的对象，判断对象的存">
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文末提到了回收机制、移除时间通知等内容，许多朋友也挺感兴趣，这次就这两个内容再来分析分析。

在开始之前先补习下 Java 自带的两个特性，Guava 中都有具体的应用。

Java 中的引用首先是 Java 中的引用。
在之前分享过 JVM 是根据可达性分析算法找出需要回收的对象，判断对象的存">
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文末提到了回收机制、移除时间通知等内容，许多朋友也挺感兴趣，这次就这两个内容再来分析分析。

在开始之前先补习下 Java 自带的两个特性，Guava 中都有具体的应用。

Java 中的引用首先是 Java 中的引用。
在之前分享过 JVM 是根据可达性分析算法找出需要回收的对象，判断对象的存">
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                Guava 源码分析（Cache 原理【二阶段】）
              
            
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        <p><img src="https://i.loli.net/2019/05/08/5cd1d2da38c8f.jpg" alt=""></p>
<h2 id="前言"><a href="#前言" class="headerlink" title="前言"></a>前言</h2><p>在上文「<a href="https://crossoverjie.top/2018/06/13/guava/guava-cache/">Guava 源码分析（Cache 原理）</a>」中分析了 <code>Guava Cache</code> 的相关原理。</p>
<p>文末提到了<strong>回收机制、移除时间通知</strong>等内容，许多朋友也挺感兴趣，这次就这两个内容再来分析分析。</p>
<blockquote>
<p>在开始之前先补习下 Java 自带的两个特性，Guava 中都有具体的应用。</p>
</blockquote>
<h2 id="Java-中的引用"><a href="#Java-中的引用" class="headerlink" title="Java 中的引用"></a>Java 中的引用</h2><p>首先是 Java 中的<strong>引用</strong>。</p>
<p>在之前分享过 JVM 是根据<a href="https://github.com/crossoverJie/Java-Interview/blob/master/MD/GarbageCollection.md#%E5%8F%AF%E8%BE%BE%E6%80%A7%E5%88%86%E6%9E%90%E7%AE%97%E6%B3%95" target="_blank" rel="external">可达性分析算法</a>找出需要回收的对象，判断对象的存活状态都和<code>引用</code>有关。</p>
<p>在 JDK1.2 之前这点设计的非常简单：一个对象的状态只有<strong>引用</strong>和<strong>没被引用</strong>两种区别。</p>
<a id="more"></a>
<p>这样的划分对垃圾回收不是很友好，因为总有一些对象的状态处于这两之间。</p>
<p>因此 1.2 之后新增了四种状态用于更细粒度的划分引用关系：</p>
<ul>
<li>强引用（Strong Reference）:这种对象最为常见，比如 <strong><code>A a = new A();</code></strong>这就是典型的强引用；这样的强引用关系是不能被垃圾回收的。</li>
<li>软引用（Soft Reference）:这样的引用表明一些有用但不是必要的对象，在将发生垃圾回收之前是需要将这样的对象再次回收。</li>
<li>弱引用（Weak Reference）:这是一种比软引用还弱的引用关系，也是存放非必须的对象。当垃圾回收时，无论当前内存是否足够，这样的对象都会被回收。</li>
<li>虚引用（Phantom Reference）:这是一种最弱的引用关系，甚至没法通过引用来获取对象，它唯一的作用就是在被回收时可以获得通知。</li>
</ul>
<h2 id="事件回调"><a href="#事件回调" class="headerlink" title="事件回调"></a>事件回调</h2><p>事件回调其实是一种常见的设计模式，比如之前讲过的 <a href="https://crossoverjie.top/categories/Netty/">Netty</a> 就使用了这样的设计。</p>
<p>这里采用一个 demo，试下如下功能：</p>
<ul>
<li>Caller 向 Notifier 提问。</li>
<li>提问方式是异步，接着做其他事情。</li>
<li>Notifier 收到问题执行计算然后回调 Caller 告知结果。</li>
</ul>
<p>在 Java 中利用接口来实现回调，所以需要定义一个接口：</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">interface</span> <span class="title">CallBackListener</span> </span>&#123;</div><div class="line"></div><div class="line">    <span class="comment">/**</span></div><div class="line">     * 回调通知函数</div><div class="line">     * <span class="doctag">@param</span> msg</div><div class="line">     */</div><div class="line">    <span class="function"><span class="keyword">void</span> <span class="title">callBackNotify</span><span class="params">(String msg)</span> </span>;</div><div class="line">&#125;</div></pre></td></tr></table></figure>
<p>Caller 中调用 Notifier 执行提问，调用时将接口传递过去：</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div><div class="line">35</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">Caller</span> </span>&#123;</div><div class="line"></div><div class="line">    <span class="keyword">private</span> <span class="keyword">final</span> <span class="keyword">static</span> Logger LOGGER = LoggerFactory.getLogger(Caller.class);</div><div class="line"></div><div class="line">    <span class="keyword">private</span> CallBackListener callBackListener ;</div><div class="line"></div><div class="line">    <span class="keyword">private</span> Notifier notifier ;</div><div class="line"></div><div class="line">    <span class="keyword">private</span> String question ;</div><div class="line"></div><div class="line">    <span class="comment">/**</span></div><div class="line">     * 使用</div><div class="line">     */</div><div class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">call</span><span class="params">()</span></span>&#123;</div><div class="line"></div><div class="line">        LOGGER.info(<span class="string">"开始提问"</span>);</div><div class="line"></div><div class="line">		<span class="comment">//新建线程，达到异步效果 </span></div><div class="line">        <span class="keyword">new</span> Thread(<span class="keyword">new</span> Runnable() &#123;</div><div class="line">            <span class="meta">@Override</span></div><div class="line">            <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">run</span><span class="params">()</span> </span>&#123;</div><div class="line">                <span class="keyword">try</span> &#123;</div><div class="line">                    notifier.execute(Caller.<span class="keyword">this</span>,question);</div><div class="line">                &#125; <span class="keyword">catch</span> (InterruptedException e) &#123;</div><div class="line">                    e.printStackTrace();</div><div class="line">                &#125;</div><div class="line">            &#125;</div><div class="line">        &#125;).start();</div><div class="line"></div><div class="line">        LOGGER.info(<span class="string">"提问完毕，我去干其他事了"</span>);</div><div class="line">    &#125;</div><div class="line">    </div><div class="line">    <span class="comment">//隐藏 getter/setter</span></div><div class="line">    </div><div class="line">&#125;</div></pre></td></tr></table></figure>
<p>Notifier 收到提问，执行计算（耗时操作），最后做出响应（回调接口，告诉 Caller 结果）。</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">Notifier</span> </span>&#123;</div><div class="line"></div><div class="line">    <span class="keyword">private</span> <span class="keyword">final</span> <span class="keyword">static</span> Logger LOGGER = LoggerFactory.getLogger(Notifier.class);</div><div class="line"></div><div class="line">    <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">execute</span><span class="params">(Caller caller, String msg)</span> <span class="keyword">throws</span> InterruptedException </span>&#123;</div><div class="line">        LOGGER.info(<span class="string">"收到消息=【&#123;&#125;】"</span>, msg);</div><div class="line"></div><div class="line">        LOGGER.info(<span class="string">"等待响应中。。。。。"</span>);</div><div class="line">        TimeUnit.SECONDS.sleep(<span class="number">2</span>);</div><div class="line"></div><div class="line"></div><div class="line">        caller.getCallBackListener().callBackNotify(<span class="string">"我在北京！"</span>);</div><div class="line"></div><div class="line">    &#125;</div><div class="line"></div><div class="line">&#125;</div></pre></td></tr></table></figure>
<p>模拟执行：</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div></pre></td><td class="code"><pre><div class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">main</span><span class="params">(String[] args)</span> </span>&#123;</div><div class="line">    Notifier notifier = <span class="keyword">new</span> Notifier() ;</div><div class="line"></div><div class="line">    Caller caller = <span class="keyword">new</span> Caller() ;</div><div class="line">    caller.setNotifier(notifier) ;</div><div class="line">    caller.setQuestion(<span class="string">"你在哪儿！"</span>);</div><div class="line">    caller.setCallBackListener(<span class="keyword">new</span> CallBackListener() &#123;</div><div class="line">        <span class="meta">@Override</span></div><div class="line">        <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">callBackNotify</span><span class="params">(String msg)</span> </span>&#123;</div><div class="line">            LOGGER.info(<span class="string">"回复=【&#123;&#125;】"</span> ,msg);</div><div class="line">        &#125;</div><div class="line">    &#125;);</div><div class="line"></div><div class="line">    caller.call();</div><div class="line">&#125;</div></pre></td></tr></table></figure>
<p>最后执行结果：</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div></pre></td><td class="code"><pre><div class="line">2018-07-15 19:52:11.105 [main] INFO  c.crossoverjie.guava.callback.Caller - 开始提问</div><div class="line">2018-07-15 19:52:11.118 [main] INFO  c.crossoverjie.guava.callback.Caller - 提问完毕，我去干其他事了</div><div class="line">2018-07-15 19:52:11.117 [Thread-0] INFO  c.c.guava.callback.Notifier - 收到消息=【你在哪儿！】</div><div class="line">2018-07-15 19:52:11.121 [Thread-0] INFO  c.c.guava.callback.Notifier - 等待响应中。。。。。</div><div class="line">2018-07-15 19:52:13.124 [Thread-0] INFO  com.crossoverjie.guava.callback.Main - 回复=【我在北京！】</div></pre></td></tr></table></figure>
<p>这样一个模拟的异步事件回调就完成了。</p>
<h2 id="Guava-的用法"><a href="#Guava-的用法" class="headerlink" title="Guava 的用法"></a>Guava 的用法</h2><p>Guava 就是利用了上文的两个特性来实现了<strong>引用回收</strong>及<strong>移除通知</strong>。</p>
<h3 id="引用"><a href="#引用" class="headerlink" title="引用"></a>引用</h3><p>可以在初始化缓存时利用：</p>
<ul>
<li>CacheBuilder.weakKeys()</li>
<li>CacheBuilder.weakValues()</li>
<li>CacheBuilder.softValues()</li>
</ul>
<p>来自定义键和值的引用关系。</p>
<p><img src="https://i.loli.net/2019/05/08/5cd1d2e161dd6.jpg" alt=""></p>
<p>在上文的分析中可以看出 Cache 中的 <code>ReferenceEntry</code> 是类似于 HashMap 的 Entry 存放数据的。</p>
<p>来看看 ReferenceEntry 的定义：</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div><div class="line">31</div><div class="line">32</div><div class="line">33</div><div class="line">34</div><div class="line">35</div><div class="line">36</div><div class="line">37</div><div class="line">38</div><div class="line">39</div><div class="line">40</div><div class="line">41</div><div class="line">42</div><div class="line">43</div><div class="line">44</div></pre></td><td class="code"><pre><div class="line">  <span class="class"><span class="keyword">interface</span> <span class="title">ReferenceEntry</span>&lt;<span class="title">K</span>, <span class="title">V</span>&gt; </span>&#123;</div><div class="line">    <span class="comment">/**</span></div><div class="line">     * Returns the value reference from this entry.</div><div class="line">     */</div><div class="line">    <span class="function">ValueReference&lt;K, V&gt; <span class="title">getValueReference</span><span class="params">()</span></span>;</div><div class="line"></div><div class="line">    <span class="comment">/**</span></div><div class="line">     * Sets the value reference for this entry.</div><div class="line">     */</div><div class="line">    <span class="function"><span class="keyword">void</span> <span class="title">setValueReference</span><span class="params">(ValueReference&lt;K, V&gt; valueReference)</span></span>;</div><div class="line"></div><div class="line">    <span class="comment">/**</span></div><div class="line">     * Returns the next entry in the chain.</div><div class="line">     */</div><div class="line">    <span class="meta">@Nullable</span></div><div class="line">    <span class="function">ReferenceEntry&lt;K, V&gt; <span class="title">getNext</span><span class="params">()</span></span>;</div><div class="line"></div><div class="line">    <span class="comment">/**</span></div><div class="line">     * Returns the entry's hash.</div><div class="line">     */</div><div class="line">    <span class="function"><span class="keyword">int</span> <span class="title">getHash</span><span class="params">()</span></span>;</div><div class="line"></div><div class="line">    <span class="comment">/**</span></div><div class="line">     * Returns the key for this entry.</div><div class="line">     */</div><div class="line">    <span class="meta">@Nullable</span></div><div class="line">    <span class="function">K <span class="title">getKey</span><span class="params">()</span></span>;</div><div class="line"></div><div class="line">    <span class="comment">/*</span></div><div class="line">     * Used by entries that use access order. Access entries are maintained in a doubly-linked list.</div><div class="line">     * New entries are added at the tail of the list at write time; stale entries are expired from</div><div class="line">     * the head of the list.</div><div class="line">     */</div><div class="line"></div><div class="line">    <span class="comment">/**</span></div><div class="line">     * Returns the time that this entry was last accessed, in ns.</div><div class="line">     */</div><div class="line">    <span class="function"><span class="keyword">long</span> <span class="title">getAccessTime</span><span class="params">()</span></span>;</div><div class="line"></div><div class="line">    <span class="comment">/**</span></div><div class="line">     * Sets the entry access time in ns.</div><div class="line">     */</div><div class="line">    <span class="function"><span class="keyword">void</span> <span class="title">setAccessTime</span><span class="params">(<span class="keyword">long</span> time)</span></span>;</div><div class="line">&#125;</div></pre></td></tr></table></figure>
<p>包含了很多常用的操作，如值引用、键引用、访问时间等。</p>
<p>根据 <code>ValueReference&lt;K, V&gt; getValueReference();</code> 的实现：</p>
<p><img src="https://i.loli.net/2019/05/08/5cd1d2e34ee46.jpg" alt=""></p>
<p>具有强引用和弱引用的不同实现。</p>
<p>key 也是相同的道理：</p>
<p><img src="https://i.loli.net/2019/05/08/5cd1d2e4ec5ff.jpg" alt=""></p>
<p>当使用这样的构造方式时，弱引用的 key 和 value 都会被垃圾回收。</p>
<p>当然我们也可以显式的回收：</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div></pre></td><td class="code"><pre><div class="line">/**</div><div class="line"> * Discards any cached value for key &#123;@code key&#125;.</div><div class="line"> * 单个回收</div><div class="line"> */</div><div class="line">void invalidate(Object key);</div><div class="line"></div><div class="line">/**</div><div class="line"> * Discards any cached values for keys &#123;@code keys&#125;.</div><div class="line"> *</div><div class="line"> * @since 11.0</div><div class="line"> */</div><div class="line">void invalidateAll(Iterable&lt;?&gt; keys);</div><div class="line"></div><div class="line">/**</div><div class="line"> * Discards all entries in the cache.</div><div class="line"> */</div><div class="line">void invalidateAll();</div></pre></td></tr></table></figure>
<h3 id="回调"><a href="#回调" class="headerlink" title="回调"></a>回调</h3><p>改造了之前的例子：</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div></pre></td><td class="code"><pre><div class="line">loadingCache = CacheBuilder.newBuilder()</div><div class="line">        .expireAfterWrite(<span class="number">2</span>, TimeUnit.SECONDS)</div><div class="line">        .removalListener(<span class="keyword">new</span> RemovalListener&lt;Object, Object&gt;() &#123;</div><div class="line">            <span class="meta">@Override</span></div><div class="line">            <span class="function"><span class="keyword">public</span> <span class="keyword">void</span> <span class="title">onRemoval</span><span class="params">(RemovalNotification&lt;Object, Object&gt; notification)</span> </span>&#123;</div><div class="line">                LOGGER.info(<span class="string">"删除原因=&#123;&#125;，删除 key=&#123;&#125;,删除 value=&#123;&#125;"</span>,notification.getCause(),notification.getKey(),notification.getValue());</div><div class="line">            &#125;</div><div class="line">        &#125;)</div><div class="line">        .build(<span class="keyword">new</span> CacheLoader&lt;Integer, AtomicLong&gt;() &#123;</div><div class="line">            <span class="meta">@Override</span></div><div class="line">            <span class="function"><span class="keyword">public</span> AtomicLong <span class="title">load</span><span class="params">(Integer key)</span> <span class="keyword">throws</span> Exception </span>&#123;</div><div class="line">                <span class="keyword">return</span> <span class="keyword">new</span> AtomicLong(<span class="number">0</span>);</div><div class="line">            &#125;</div><div class="line">        &#125;);</div></pre></td></tr></table></figure>
<p>执行结果：</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div></pre></td><td class="code"><pre><div class="line">2018-07-15 20:41:07.433 [main] INFO  c.crossoverjie.guava.CacheLoaderTest - 当前缓存值=0,缓存大小=1</div><div class="line">2018-07-15 20:41:07.442 [main] INFO  c.crossoverjie.guava.CacheLoaderTest - 缓存的所有内容=&#123;1000=0&#125;</div><div class="line">2018-07-15 20:41:07.443 [main] INFO  c.crossoverjie.guava.CacheLoaderTest - job running times=10</div><div class="line">2018-07-15 20:41:10.461 [main] INFO  c.crossoverjie.guava.CacheLoaderTest - 删除原因=EXPIRED，删除 key=1000,删除 value=1</div><div class="line">2018-07-15 20:41:10.462 [main] INFO  c.crossoverjie.guava.CacheLoaderTest - 当前缓存值=0,缓存大小=1</div><div class="line">2018-07-15 20:41:10.462 [main] INFO  c.crossoverjie.guava.CacheLoaderTest - 缓存的所有内容=&#123;1000=0&#125;</div></pre></td></tr></table></figure>
<p>可以看出当缓存被删除的时候会回调我们自定义的函数，并告知删除原因。</p>
<p>那么 Guava 是如何实现的呢？</p>
<p><img src="https://i.loli.net/2019/05/08/5cd1d2e5d3a34.jpg" alt=""></p>
<p>根据 LocalCache 中的 <code>getLiveValue()</code> 中判断缓存过期时，跟着这里的调用关系就会一直跟到：</p>
<p><img src="https://i.loli.net/2019/05/08/5cd1d2e71f98f.jpg" alt=""></p>
<p><code>removeValueFromChain()</code> 中的：</p>
<p><img src="https://i.loli.net/2019/05/08/5cd1d2e809482.jpg" alt=""></p>
<p><code>enqueueNotification()</code> 方法会将回收的缓存（包含了 key，value）以及回收原因包装成之前定义的事件接口加入到一个<strong>本地队列</strong>中。</p>
<p><img src="https://i.loli.net/2019/05/08/5cd1d2e8e1800.jpg" alt=""></p>
<p>这样一看也没有回调我们初始化时候的事件啊。</p>
<p>不过用过队列的同学应该能猜出，既然这里写入队列，那就肯定就有消费。</p>
<p>我们回到获取缓存的地方：</p>
<p><img src="https://i.loli.net/2019/05/08/5cd1d2eba7159.jpg" alt=""></p>
<p>在 finally 中执行了 <code>postReadCleanup()</code> 方法；其实在这里面就是对刚才的队列进行了消费：</p>
<p><img src="https://i.loli.net/2019/05/08/5cd1d2f1e162f.jpg" alt=""></p>
<p>一直跟进来就会发现这里消费了队列，将之前包装好的移除消息调用了我们自定义的事件，这样就完成了一次事件回调。</p>
<h2 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h2><p>以上所有源码：</p>
<p><a href="https://github.com/crossoverJie/Java-Interview/blob/master/src/main/java/com/crossoverjie/guava/callback/Main.java" target="_blank" rel="external">https://github.com/crossoverJie/Java-Interview/blob/master/src/main/java/com/crossoverjie/guava/callback/Main.java</a></p>
<p>通过分析 Guava 的源码可以让我们学习到顶级的设计及实现方式，甚至自己也能尝试编写。</p>
<p>Guava 里还有很多强大的增强实现，值得我们再好好研究。</p>
<h2 id="号外"><a href="#号外" class="headerlink" title="号外"></a>号外</h2><p>最近在总结一些 Java 相关的知识点，感兴趣的朋友可以一起维护。</p>
<blockquote>
<p>地址: <a href="https://github.com/crossoverJie/Java-Interview" target="_blank" rel="external">https://github.com/crossoverJie/Java-Interview</a></p>
</blockquote>
<p><strong>欢迎关注公众号一起交流：</strong></p>

      
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